Many varieties of round balers are currently commercially available. A frequently encountered problem, however, involves the fact that the width of the baling chambers on such machines is typically greater than the width of the crop windrow along which the baler is driven. Consequently, in order to avoid an oddly shaped bale and to be assured that the chamber will be evenly loaded with material from end-to-end, many manufacturers instruct the operator to weave back-and-forth across the windrow as he drives along. This requires considerable operator attention and necessitates having the operator look back over his shoulder frequently in an effort to inspect the bale chamber, instead of watching ahead and being on the alert for possible danger.
Moreover, even though the bale may appear to be uniform in diameter, the density of the bale may be non-uniform. This lack of uniform density leads to a reduction in the total weight per bale and to an increase in spoilage when the bales are stored outside. During nighttime baling, which is a common practice for alfalfa hay during hot summer months, the problem is exacerbated because it is even more difficult for the operator to clearly see what is happening in the bale chamber under low light conditions. Spot lights which may be installed in and around the baler can often provide a glare which further compounds the problem.
Several efforts have been made to improve the state of the art in this respect including, for example, the system disclosed in U.S. Pat. No. 4,224,867, issued in the name of Gaeddert et al on Sept. 30, 1980. This patent is directed to the concept of producing a signal as a result of sensing a lack of uniform crop distribution in the baling chamber. Such signal may be used to power warning lights and the like in the cab of the tractor whereby to alert the operator to the need for taking appropriate weaving action. While alerting the operator through a warning device solves part of the problem, it still requires overt action by the operator in response to his realization that the bale chamber is not filling evenly.
U.S. Pat. No. 4,065,914, issued Jan. 3, 1978, in the name of Phillips et al, discloses the concept of driving the tractor straight down the windrow but then having a control at the tractor seat which permits the operator to steer the baler and cause it to weave relative to the tractor so that the baler can then introduce the narrow windrow successively across all portions of the chamber. However, this, too, requires constant operator attention.
U.S. Pat. No. 4,433,533, issued in the name of Giani on Feb. 28, 1984, discloses the concept of weaving the baler behind the tractor in an automatic manner without driver attention by virtue of sensors which detect the need for crop in the various portions of the chamber and then cause the baler to be weaved or turned accordingly. However, in this machine the large mass of the baler would apparently have a detrimental effect on the response time of the control system involved; moreover, the system is not totally insulated from adverse positioning of the tractor relative to the windrow. In other words, even though the baler might automatically shift in one direction in response to a need, there is nothing to prevent the operator from inadvertently drifting the tractor in the opposite direction, thereby reducing or effectively cancelling out the repositioning shift of the baler. To a certain extent, then, even in this system the extent of uniform loading in the bale chamber is dependent upon the operator maintaining a proper position along the windrow.